A new technology, scanning laser polarimetry, will be employed to measure absolute thickness of the retinal nerve fiber layer in order to detect early damage from glaucoma and other optic neuropathies. This new test is based on the polarization properties of the parallel, form- birefringent nerve fibers and can be applied through the undilated pupil. A clinical instrument has been designed that allows to measure retinal nerve fiber layer thickness at over 65,000 retinal locations in about .7 seconds. The proposed research will validate this technology by comparing the measurements with this new instrument to known properties of the human retinal nerve fiber layer and other, conventional methods of diagnosing glaucoma. The long-term goal of this research is to develop a rapid, convenient, objective screening tool for early detection and accurate follow-up of glaucoma. PROPOSED COMMERCIAL APPLICATION: Potentially, this research will lead to the development of a sensitive, easy-to-use, rapid (under 1 second), and convenient (no pupil dilation) test to diagnoses glaucoma earlier than currently possible.